Asymmetric angular response pixels for single sensor stereo

ABSTRACT

Depth sensing imaging pixels include pairs of left and right pixels forming an asymmetrical angular response to incident light. A single microlens is positioned above each pair of left and right pixels. Each microlens spans across each of the pairs of pixels in a horizontal direction. Each microlens has a length that is substantially twice the length of either the left or right pixel in the horizontal direction; and each microlens has a width that is substantially the same as a width of either the left or right pixel in a vertical direction. The horizontal and vertical directions are horizontal and vertical directions of a planar image array. A light pipe in each pixel is used to improve light concentration and reduce cross talk.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority of U.S. Provisional Patent ApplicationSer. No. 61/522,876, filed Aug. 12, 2011, which is incorporated hereinby reference.

FIELD OF THE INVENTION

The present invention relates, in general, to imaging systems. Morespecifically, the present invention relates to imaging systems withdepth sensing capabilities and stereo perception, although using only asingle sensor with a single lens.

BACKGROUND OF THE INVENTION

Modern electronic devices such as cellular telephones, cameras, andcomputers often use digital image sensors. Imagers (i.e., image sensors)may be formed from a two-dimensional array of image sensing pixels. Eachpixel receives incident photons (light) and converts the photons intoelectrical signals.

Some applications, such as three-dimensional (3D) imaging may requireelectronic devices to have depth sensing capabilities. For example, toproperly generate a 3D image for a given scene, an electronic device mayneed to identify the distances between the electronic device and objectsin the scene. To identify distances, conventional electronic devices usecomplex arrangements. Some arrangements require the use of multiplecameras with multiple image sensors and lenses that capture images fromvarious viewpoints. These increase cost and complexity in obtaining goodstereo imaging performance. Other arrangements require the addition oflenticular arrays that focus incident light on sub-regions of atwo-dimensional pixel array. Due to the addition of components, such ascomplex lens arrays, these arrangements lead to reduced spatialresolution, increased cost and complexity.

The present invention, as will be explained, addresses an improvedimager that obtains stereo performance using a single sensor with asingle lens. Such imager reduces complexity and cost, and improves thestereo imaging performance.

BRIEF DESCRIPTION OF THE FIGURES

The invention may be best understood from the following detaileddescription when read in connection with the accompanying figures:

FIG. 1 is a schematic diagram of an electronic device with a camerasensor that may include depth sensing pixels, in accordance with anembodiment of the present invention.

FIG. 2A is a cross-sectional view of a pair of depth sensing pixelscovered by one microlens that has an asymmetric angular response, inaccordance with an embodiment of the present invention.

FIGS. 2B and 2C are cross-sectional views of a depth sensing pixel thatmay be asymmetrically sensitive to incident light at negative andpositive angles of incidence, in accordance with an embodiment of thepresent invention.

FIG. 2D shows a cross-sectional view and a top view of a pair of depthsensing pixels covered by one microlens, in accordance with anembodiment of the present invention.

FIG. 3 is a diagram of illustrative output signals of a depth sensingpixel for incident light striking the depth sensing pixel at varyingangles of incidence, in accordance with an embodiment of the presentinvention.

FIG. 4 is a diagram of illustrative output signals of depth sensingpixels in a depth sensing pixel pair for incident light striking thedepth sensing pixel pair at varying angles of incidence, in accordancewith an embodiment of the present invention.

FIG. 5A is a diagram of a depth sensing imager having a lens and anobject located at a focal distance away from the lens, showing how thelens focuses light from the object onto the depth sensing imager, inaccordance with an embodiment of the present invention.

FIG. 5B is a diagram of a depth sensing imager having a lens and anobject located at more than a focal distance away from the lens, showinghow the lens focuses light from the object onto the depth sensingimager, in accordance with an embodiment of the present invention.

FIG. 5C is a diagram of a depth sensing imager having a lens and anobject located less than a focal distance away from the imaging lens,showing how the lens focuses light from the object onto the depthsensing imager, in accordance with an embodiment of the presentinvention.

FIG. 6 is a diagram of illustrative depth output signals of a depthsensing pixel pair for an object at varying distances from the depthsensing pixel, in accordance with an embodiment of the presentinvention.

FIG. 7 is a perspective view of one microlens covering two depth sensingpixels, in accordance with an embodiment of the present invention.

FIG. 8 is a diagram showing a top view of two sets of two depth sensingpixels of FIG. 7 arranged in a Bayer pattern, in accordance with anembodiment of the present invention.

FIG. 9 is diagram of a cross-sectional view of two sets of two depthsensing pixels, showing light entering one light pipe (LP) in each set,in accordance with an embodiment of the present invention.

FIG. 10 is diagram of a side view of the two sets of two depth sensingpixels shown in FIG. 9.

FIG. 11 is plot of the relative signal response versus the incidentangle of light entering left and right pixels in each set of pixelsshown in FIG. 9, in accordance with an embodiment of the presentinvention.

FIG. 12 is a top view of sets of left and right pixels arranged in aBayer pattern, in accordance with an embodiment of the presentinvention.

FIGS. 13A and 13B are top views of sets of left and right pixelsarranged differently so that each forms a Bayer pattern, in accordancewith an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

An electronic device with a digital camera module is shown in FIG. 1.Electronic device 10 may be a digital camera, a computer, a cellulartelephone, a medical device, or other electronic device. Camera module12 may include image sensor 14 and one or more lenses. During operation,the lenses focus light onto image sensor 14. Image sensor 14 includesphotosensitive elements (i.e., pixels) that convert the light intodigital data. Image sensors may have any number of pixels (e.g.,hundreds, thousands, millions, or more). As examples, image sensor 14may include bias circuitry (e.g., source follower load circuits), sampleand hold circuitry, correlated double sampling (CDS) circuitry,amplifier circuitry, analog-to-digital converter (ADC) circuitry, dataoutput circuitry, memory (e.g., buffer circuitry), address circuitry,etc.

Still and video image data from camera sensor 14 may be provided toimage processing and data formatting circuitry 16 via path 26. Imageprocessing and data formatting circuitry 16 may be used to perform imageprocessing functions such as data formatting, adjusting white balanceand exposure, implementing video image stabilization, face detection,etc. Image processing and data formatting circuitry 16 may also be usedto compress raw camera image files, if desired (e.g., to JointPhotographic Experts Group, or JPEG format). In a typical arrangement,which is sometimes referred to as a system-on-chip, or SOC arrangement,camera sensor 14 and image processing and data formatting circuitry 16are implemented on a common integrated circuit. The use of a singleintegrated circuit to implement camera sensor 14 and image processingand data formatting circuitry 16 may help to minimize costs.

Camera module 12 (e.g., image processing and data formatting circuitry16) conveys acquired image data to host subsystem 20 over path 18.Electronic device 10 typically provides a user with numerous high-levelfunctions. In a computer or advanced cellular telephone, for example, auser may be provided with the ability to run user applications. Toimplement these functions, host subsystem 20 of electronic device 10 mayhave input-output devices 22, such as keypads, input-output ports,joysticks, displays, and storage and processing circuitry 24. Storageand processing circuitry 24 may include volatile and nonvolatile memory(e.g., random-access memory, flash memory, hard drives, solid statedrives, etc.). Storage and processing circuitry 24 may also includemicroprocessors, microcontrollers, digital signal processors,application specific integrated circuits, etc.

It may be desirable to form image sensors with depth sensingcapabilities (e.g., for use in 3D imaging applications, such as machinevision applications and other three dimensional imaging applications).To provide depth sensing capabilities, camera sensor 14 may includepixels such as pixels 100A, and 100B, shown in FIG. 2A.

FIG. 2A shows an illustrative cross-section of pixels 100A and 100B.Pixels 100A and 100B may contain microlens 102, color filter 104, astack of dielectric layers 106, substrate layer 108, a photosensitivearea, such as photosensitive area 110A and 110B formed in substratelayer 108, and pixel separating areas 112 formed in substrate layer 108.

Microlens 102 may direct incident light towards a substrate area betweenpixel separators 112. Color filter 104 may filter the incident light byonly allowing predetermined wavelengths to pass through color filter 104(e.g., color filter 104 may only be transparent to wavelengthscorresponding to a green color). Photo-sensitive areas 110A and 110B mayserve to absorb incident light focused by microlens 102 and produceimage signals that correspond to the amount of incident light absorbed.

A pair of pixels 100A and 100B may be covered by one microlens 102.Thus, the pair of pixels may be provided with an asymmetric angularresponse (e.g., pixels 100A and 100B may produce different image signalsbased on the angle at which incident light reaches pixels 100A and100B). The angle at which incident light reaches pixels 100A and 100Bmay be referred to herein as an incident angle, or angle of incidence.

In the example of FIG. 2B, incident light 113 may originate from theleft of a normal axis 116 and may reach a pair of pixels 100A and 100Bwith an angle 114 relative to normal axis 116. Angle 114 may be anegative angle of incident light. Incident light 113 that reachesmicrolens 102 at a negative angle, such as angle 114, may be focusedtowards photosensitive area 110A, and pixel 100A may produce relativelyhigh image signals.

In the example of FIG. 2C, incident light 113 may originate from theright of normal axis 116 and reach the pair of pixels 100A and 100B withan angle 118 relative to normal axis 116. Angle 118 may be a positiveangle of incident light.

Incident light that reaches microlens 102 at a positive angle, such asangle 118, may be focused towards photosensitive area 110B. In thiscase, pixel 100B may produce an image signal output that is relativelyhigh.

Due to the special formation of the microlens, pixels 100A and 100B mayhave an asymmetric angular response (e.g., pixel 100A and 100B mayproduce different signal outputs for incident light with a givenintensity, based on an angle of incidence). In the diagram of FIG. 3, anexample of the image output signals of pixel 100A in response to varyingangles of incident light are shown. As shown, pixel 100A may producelarger image signals for negative angles of incident light and smallerimage signals for positive angles of incident light. In other words,pixel 100A produces larger image signals as the incident angle becomesmore negative.

FIG. 2D illustrates an adjacent pair of pixels (100A and 100B) with thesame microlens, in which pixel 100A is formed on the right side of thepair, and pixel 100B is formed on the left side of the pair. An adjacentpair of pixels, such as pixels 100A and 100B, may be referred to hereinas pixel pair 200. The pixel pair 200 may also be referred to herein aspixel type 1 and pixel type 2.

Incident light 113 that reaches pair of pixels 100A and 100B may have anangle of incidence that is approximately equal for both pixels. In thearrangement of FIG. 2D, incident light 113 may be focused by microlens102A onto photosensitive area 110B in pixel 100A and photosensitive area110B in pixel 100B. In response to receiving incident light 113, pixel100A may produce an output image signal that is high and pixel 100B mayproduce an output image signal that is high by the microlens design.

The respective output image signals for pixel pair 200 (e.g., pixels100A and 100B) are shown in FIG. 4. As shown, line 160 may reflect theoutput image signal for pixel 100A and line 162 may reflect the outputimage signal for pixel 100B. For negative angles of incidence, theoutput image signal for pixel 100A may increase (because incident lightis focused onto photosensitive area 110A of pixel 100A) and the outputimage signal for pixel 100B may decrease (because incident light isfocused away from photosensitive area 110B of pixel 100B). For positiveangles of incidence, the output image signal for pixel 100A may berelatively small and the output image signal for pixel 100B may berelatively large (e.g., the output signal from pixel 100A may decreaseand the output signal from pixel 100B may increase).

Line 164 of FIG. 4 may reflect the sum of the output signals for pixelpair 200. As shown, line 164 may remain relatively constant regardlessof the angle of incidence (e.g., for any given angle of incidence, thetotal amount of light that is absorbed by the combination of pixels 100Aand 100B may be constant).

Pixel pairs 200 may be used to form imagers with depth sensingcapabilities. FIGS. 5A, 5B and 5C show illustrative image sensors 14with depth sensing capabilities. As shown, image sensor 14 may containan array of pixels 201 formed from pixel pairs 200 (e.g., pixel pairs200A, 200B, 200C, etc.). Image sensor 14 may have an associated cameralens 202 that focuses light originating from a scene of interest (e.g.,a scene that includes an object 204) onto the array of pixels. Cameralens 202 may be located at a distance D_(F) from image sensor 14.Distance D_(F) may correspond to the focal length of camera lens 202.

In the arrangement of FIG. 5A, object 204 may be located at distance D₀from camera lens 202. Distance D₀ may correspond to a focused objectplane of camera lens 202 (e.g., a plane located at a distance D_(o) fromcamera lens 202). The focused object plane and a plane corresponding toimage sensor 14 may sometimes be referred to as conjugate planes. Inthis case, light from object 204 may be focused onto pixel pair 200A, atan angle θ₀ and an angle −θ₀. The image output signals of pixels 100Aand 100B of pixel pair 200 may be equal (e.g., most of the light isabsorbed by pixel 100A for the positive angle and most of the light isabsorbed by pixel 100B for the negative angle).

In the arrangement of FIG. 5B, object 204 may be located at a distanceD₁ from camera lens 202. Distance D₁ may be larger than the distance ofthe focused object plane (e.g., the focused object plane correspondingto distance D₀) of camera lens 202. In this case, some of the light fromobject 204 may be focused onto pixel pair 200B at a negative angle−θ₁(e.g., the light focused by the bottom half pupil of camera lens 202)and some of the light from object 204 may be focused onto pixel pair200C at a positive angle θ₁ (e.g., the light focused by the top halfpupil of camera lens 202).

In the arrangement of FIG. 5C, object 204 may be located at a distanceD₂ from camera lens 202. Distance D₂ may be smaller than the distance ofthe focused object plane (e.g., the focused object plane correspondingto distance D₀) of camera lens 202. In this case, some of the light fromobject 204 may be focused by the top half pupil of camera lens 202 ontopixel pair 200B at a positive angle θ₂ and some of the light from object204 may be focused by the bottom half pupil of camera lens 202 ontopixel pair 200C at a negative angle −θ₂.

The arrangements of FIGS. 5A, 5B and 5C may effectively partition thelight focused by camera lens 202 into two halves split by a center planeat a midpoint between the top of the lens pupil and the bottom of thelens pupil (e.g., split into a top half and a bottom half). Each pixelin the paired pixel array 201 may receive different amounts of lightfrom top or bottom half of the lens pupil, respectively. For example,for an object at distance D₁, pixel 100A of 200B may receive more lightthan pixel 100B of 200B. For an object at distance D₂, pixel 100A of200B may receive less light than 100B of 200B. The partitioning of thelight focused by camera lens 202 may be referred to herein as lenspartitioning, or lens pupil division.

The output image signals of each pixel pair 200 of image sensor 14 maydepend on the distance from camera lens 202 to object 204. The angle atwhich incident light reaches pixel pairs 200 of image sensor 14 dependson the distance between lens 202 and objects in a given scene (e.g., thedistance between objects such as object 204 and device 10).

An image depth signal may be calculated from the difference between thetwo output image signals of each pixel pair 200. The diagram of FIG. 6shows an image depth signal that may be calculated for pixel pair 200Bby subtracting the image signal output of pixel 100B from the imagesignal output of pixel 100A (e.g., by subtracting line 162 from line 160of FIG. 4). As shown in FIG. 6, for an object at a distance that is lessthan distance D₀, the image depth signal may be negative. For an objectat a distance that is greater than the focused object distance D₀, theimage depth signal may be positive.

For distances greater than D₄ and less than D₃, the image depth signalmay remain constant. Pixels 100A and 100B may be unable to resolveincident angles with magnitudes larger than the magnitudes of anglesprovided by objects at distances greater than D₄, or at distances lessthan D₃. In other words, a depth sensing imager may be unable toaccurately measure depth information for objects at distances greaterthan D₄, or at distances less than D₃. The depth sensing imager may beunable to distinguish whether an object is at a distance D₄ or adistance D₅ (as an example). If desired, the depth sensing imager mayassume that all objects that result in an image depth signal equivalentto distance D₂ or D₄ are at a distance of D₂ or D₄, respectively.

To provide an imager 14 with depth sensing capabilities, two dimensionalpixel arrays 201 may be formed from various combinations of depthsensing pixel pairs 200 and regular pixels (e.g., pixels withoutasymmetric angular responses). For a more comprehensive description oftwo dimensional pixel arrays 201, with depth sensing capabilities andwith regular pixels (e.g., pixels without asymmetric angular responses),reference is made to Application Ser. No. 13/188,389, filed on Jul. 21,2011, titled Imagers with Depth Sensing Capabilities, having commoninventors. That application is incorporated herein by reference in itsentirety.

It should be understood that the depth sensing pixels may be formed withany desirable types of color filters. Depth sensing pixels may be formedwith red color filters, blue color filters, green color filters, orcolor filters that pass other desirable wavelengths of light, such asinfrared and ultraviolet light wavelengths. If desired, depth sensingpixels may be formed with color filters that pass multiple wavelengthsof light. For example, to increase the amount of light absorbed by adepth sensing pixel, the depth sensing pixel may be formed with a colorfilter that passes many wavelengths of light. As another example, thedepth sensing pixel may be formed without a color filter (sometimesreferred to as a clear pixel).

Referring now to FIG. 7, there is shown a perspective view of anembodiment of the present invention. The pixel pair 302 is similar tothe pixel pair 200 shown in FIG. 2D. The pixel pair includes left andright pixels, or as sometimes referred to as pixel type-one and pixeltype-two. As shown in FIG. 7, a single microlens 300 (same as 102 inFIG. 2D) is positioned above the left and right pixels so that thesingle microlens spans across both pixels in the horizontal direction.

Several pixel pairs 302 are shown in FIG. 8. Each pixel pair includes asingle color filter of a CFA (color filter array) that forms a Bayerpattern. Pixel pair 302A forms two color filters for green. Pixel pair302B forms two color filters for blue. Pixel pair 302C forms two greenfilters. Similarly, pixel pairs 302D, 302E, 302F, 302G and 302H formpairs of color filters producing a Bayer pattern.

Referring now to FIG. 9, there is shown an asymmetric pixelconfiguration that includes microlens 300 and pixel pair 302, similar tothe pixel configuration of FIG. 7. It will be appreciated that FIG. 9shows four pixels, namely, pixels 316A and 316B forming one pair ofpixels on the left side of the figure and pixels 316A and 316B forminganother pair of pixels on the right side of the figure. As shown, eachmicrolens 300 covers two pixels in the horizontal direction. Aplanarization layer 310 is disposed under each microlens 300. Belowplanarization layer 310, there is shown a color filter which spansacross two pixels 316A and 316B. Thus, color filter 312 is similar inlength to the length of microlens 300 and covers a pixel pair (or a setof pixels).

Disposed between each color filter 312 and each pixel pair 316A and 316Bare two light pipes (LPs). Each LP improves the light concentration thatimpinges upon each respective pixel. The LP improves, not only the lightconcentration, but also reduces cross-talk and insures good threedimensional performance, even with very small pixel pitches, such as 1.4microns or less.

As shown on the left side of FIG. 9, light enters pixel photosensitivearea 316B by way of LP 314B. Similarly, on the right side of FIG. 9,light enters LP 314A and pixel photosensitive area 316A. It will beappreciated that LP 314B, on the left side of the figure, includes mostof the light, because the light passing through microlens 300 is angledat a negative angle with respect to a vertical line through microlens300. In a similar way, the light on the right side of the figure, entersLP 314A, because the light passing through microlens 300 is angled at apositive angle with respect to a vertical line through microlens 300.

FIG. 10 shows the same pixels as in FIG. 9, except that a side-view isshown of the pixel pair. As shown, microlens 300 only spans one pixel inthe vertical direction, or the column direction of a pixel array.Accordingly, microlens 300 is effective in reducing cross-talk in thevertical direction of the pixel array. Also shown in the figure is aside-view of LP 314 and pixel photosensitive area 316. In addition,light is shown concentrated in LP 314 and passing into pixelphotosensitive area 316.

FIG. 11 shows the relative signal response versus the incident angle oflight entering a pixel pair. As shown, the right pixel (or pixel 314B onthe left side of FIG. 9) responds strongly, when the light enters at anegative angle with respect to a vertical line passing through microlens300. On the other hand, when the left pixel (or pixel 314A on the rightside of FIG. 9) receives light at a positive angle with respect to anormal passing through microlens 300, the pixel also responds strongly.At normal incidence, however, the responses of the left and right pixelsare relatively low. It will be appreciated that if the two pixelsforming each pixel pair is summed in the horizontal direction, a normalimage may be formed. On the other hand, since the left and right pixelsform asymmetric pixel angular responses, the present invention obtainsdepth sensing capabilities.

It will now be understood that an asymmetric angular response stereosensor is provided by the present invention. By having a 2×1 CFApattern, as shown in FIG. 8, the present invention may process the colornormally for two separate images and obtain two separate Bayer patterns,as shown in FIG. 12. Accordingly, the two pixel pairs shown on the leftside of FIG. 12 may be separated into two images (the left image has twopixels and the right image has two pixels).

For example, the first pixel pair provides a green color; when the pairis separated into left and right images, the present invention providesa single green pixel for the left image and a single green pixel for theright image. Similarly, when the two right pixels providing red colorsare separated into left and right images, the present invention forms aleft image with a red color and a right image with a red color. Thus, a2×1 CFA pattern enables the present invention to form a normal Bayercolor process for two separate images (left and right Bayer images), asshown in FIG. 12.

Referring next to FIGS. 13A and 13B, there are shown two differentCFA/microlens arrangements, namely arrangement 1 in FIG. 13A andarrangement 2 in FIG. 13B. It will be appreciated that each arrangementincludes microlenses that cover 2×1 pixels, as shown in FIG. 7. Themicrolenses, however, are shown zigzag-shifted relative to each other byone pixel in neighboring rows. These arrangement result in no resolutionloss in the horizontal direction and would be valuable for HD videoformat.

In arrangement 1 shown in FIG. 13A, the first and second rows' CFApattern is GRGRGR . . . , and the third and fourth rows' CFA patterns isBGBGBG . . . . The 2×1 microlens for the first and third rows start fromthe first column, whereas the microlens for the second and fourth rowsstart one column earlier, or later. Therefore, the left image pixelarray is formed by pixels L1, L2, L3, L4, L5, L6, L7 and L8. Similarly,the right image pixel array is formed by pixels R1, R2, R3, R4, R5, R6,R7 and R8. The first Bayer pattern for the left image is formed by Gr=L1in the first row, R=L2 in the second row, B=L1 in the third row, andGb=L2 in the fourth row. The first Bayer pattern for the right image isformed by Gr=R1 in the second row, R=R2 in the first row, B=R1 in thefourth row, and Gb=R2 in the third row.

In arrangement 2, shown in FIG. 13B, the first and third rows are an allgreen CFA, the second row is an all red CFA, and the fourth row is anall blue CFA. The 2×1 microlens for the first and third rows start fromthe first column, whereas the microlens for second and fourth rows startone column earlier, or later. Therefore, the left image pixel array isformed by pixels L1, L2, L3, L4, L5, L6, L7 and L8. Similarly, the rightimage pixel array is formed by pixels R1, R2, R3, R4, R5, R6, R7 and R8.The first Bayer pattern for the left image is formed by Gr=L1 in thefirst row, R=L2 in the second row, Gb=L1 in the third row, and B=L2 inthe fourth row. The first Bayer pattern for the right image is formed byGr=R1 in the first row, R=R2 in the second row, Gb=R1 in the third rowand B=R2 in the fourth row.

Referring again to FIGS. 9 and FIG. 10, it will be understood that eachmicrolens covers two pixels in the horizontal direction, but only coversone pixel in the vertical direction. Furthermore, the radius ofcurvature of each microlens in both directions are different due toprocessing limitations. The microlens material includes an optical index(n) that varies in range between 1.5 and 1.6. Furthermore, the LP may befilled by material having a higher optical index (n greater than 1.6)than its surrounding oxide material, in which the latter may have anoptical index of 1.4 or 1.5. In this manner, the light is maintainedwithin the LP.

Although the invention is illustrated and described herein withreference to specific embodiments, the invention is not intended to belimited to the details shown. Rather, various modifications may be madein the details within the scope and range of equivalents of the claimsand without departing from the invention.

1. Depth sensing imaging pixels comprising: left and right pixelsforming an asymmetrical angular response to incident light, and a singlemicrolens positioned above the left and right pixels, wherein the singlemicrolens spans across the left and right pixels in a horizontaldirection.
 2. The imaging pixels of claims 1 wherein the singlemicrolens has a length that is substantially twice the length of eitherthe left or right pixel in the horizontal direction, and the singlemicrolens has a width that is substantially the same as a width ofeither the left or right pixel in a vertical direction; wherein thehorizontal and vertical directions are horizontal and verticaldirections of a planar image array.
 3. The imaging pixels of claim 2wherein the single microlens has a radius of curvature in the horizontaldirection that is the same or different from its radius of curvature inthe vertical direction.
 4. The imaging pixels of claim 1 including: acolor filter disposed between the single microlens and the left andright pixels.
 5. The imaging pixels of claim 4 wherein the color filterspans across the left and right pixels in the horizontal direction. 6.The imaging pixels of claim 5 wherein the color filter has a length thatis substantially twice the length of either the left or right pixel inthe horizontal direction, and the color filter has a width that issubstantially the same as a width of either the left or right pixel inthe vertical direction, wherein the horizontal and vertical directionsare horizontal and vertical directions of a planar image array.
 7. Theimaging pixels of claim 5 wherein the color filter is configured toprovide one of the following in a CFA pattern: (a) left and right Bayerimages for two separated images, and (b) a single Bayer image for asingle image, in which the left and right pixels are summed together. 8.The imaging pixels of claim 1 including a left light pipe (LP) disposedbetween the left pixel and the single microlens for directing theincident light toward the left pixel, and a right light pipe (LP)disposed between the right pixel and the single microlens for directingthe incident light toward the right pixel.
 9. The imaging pixels ofclaim 8 wherein the left light pipe is configured to receive theincident light at a relatively high signal response, when the incidentlight forms a positive angle with respect to a vertical plane passingbetween the left and right pixels, and the right light pipe isconfigured to receive the incident light at a relatively high signalresponse, when the incident light forms a negative angle with respect toa vertical plane passing between the left and right pixels.
 10. Theimaging pixels of claim 8 wherein the left and right light pipes includematerial of a refractive index greater than a refractive index ofmaterial external of the left and right light pipes.
 11. An imagingarray comprising: multiple pixel pairs of left and right pixels, eachpixel pair forming an asymmetrical angular response to incident light,and multiple color filters disposed on top of the multiple pixel pairs,wherein the multiple color filters provide at least one Bayer colorpattern and each color filter spans across one pixel pair.
 12. Theimaging array of claim 11 wherein the multiple pixel pairs areconfigured to provide one of the following: (a) two separate images, oneimage derived from left pixels and the other image derived from rightpixels, and (b) a single image upon summing respective left and rightpixels in each of the multiple pixel pairs.
 13. The imaging array ofclaim 11 including: multiple microlenses covering the multiple pixelpairs, wherein each microlens covers 2×1 pixels, defining two pixels ina row and one pixel in a column.
 14. The imaging array of claim 13wherein each microlens in a row is shifted by one pixel relative to eachmicrolens in a neighboring row.
 15. The imaging array of claim 14wherein two separate patterns are formed, in which left and right imagearrays are formed from neighboring four rows.
 16. The imaging array ofclaim 11 including multiple light pipes disposed between the multiplepixel pairs and multiple color filters, wherein each light pipe isconfigured to direct the incident light toward one of either a leftpixel or a right pixel.
 17. An imaging array for a camera comprising:multiple pixel pairs forming rows and columns of a focal planar array(FPA), each pixel pair including left and right pixels forming anasymmetrical angular response to incident light, and multiple lightpipes (LP) disposed within the multiple pixel pairs, wherein each LP isconfigured to direct the incident light toward one of either left orright pixels of respective pixel pairs.
 18. The imaging array of claim17 including: multiple color filters disposed above the multiple LPs,wherein the multiple color filters are configured to provide at leastone Bayer color pattern, and each color filter spans across each pixelpair.
 19. The imaging array of claim 18 including: multiple microlensesdisposed above the multiple color filters, wherein each microlens covers2×1 pixels, the 2×1 pixels defining a pixel pair.
 20. The imaging arrayof claim 19 wherein each microlens in a row of the FPA is zigzag shiftedby one pixel relative to each microlens in a neighboring row, a leftimaging array in four adjacent rows form a Bayer pattern, and a rightimaging array in four adjacent rows form another Bayer pattern.